Usually, inorganic particles and organic particles called external additives are added to the surface of the toner used for electrophotographic image formation in order to realize good image formation. It is designed to maintain toner performance such as chargeability and fluidity by the action of external additives. Among the compounds used as external additives, there are titanic acid compounds represented by calcium titanate and strontium titanate. For example, Patent Document 1 (JP-A 11-237766) discloses a toner using a titanic acid compound as an external additive. It has been known that such a toner contributes to the prevention of filming on the surface of the photoreceptor and improvement of cleaning property during image formation. In addition, the polishing action possessed by the titanic acid compound is drawing attention, and it has been known that the surface of the photoreceptor is sufficiently polished by the titanic acid compound added as an external additive to the toner in order to maintain the image forming performance.
However, the titanic acid compound has too strong abrasive properties, so that the surface of the photoreceptor may be coarsely worn or scratched. This is not preferable from the viewpoint of obtaining good image quality, such as streaky noise and density unevenness occurring on a solid image or a halftone image. Particularly, in recent years, due to progress of digitization, there are increasing cases where image formation with high gradation and high definition image quality, such as a photographic image composed of fine dot images. For this reason, image defects caused by damage of the photosensitive member produced by polishing must be avoided.